Metal pipe having through-wall slots, referred to as “slotted liners”, are commonly used to line bore holes in porous earth formations to exclude entry of solid particles while permitting fluid flow through the liner wall. As is well known in the art, the selection of slotting geometry affects the structural capacity of the slotted liner in addition to its filtering characteristics. The selection of slot geometry thus typically considers the impact of slotting on the usual structural properties of axial, torsion and collapse load capacities. U.S. Pat. No. 1,620,412 (Tweeddale 1927) is an example of an early patent in which the importance of slot geometry was recognized.